In this article, an excerpt from Beginning Java EE 5 (Apress, October 2005; ISBN: 1590594703), authors Jim Crume, Kevin Mukhar, James Weaver, and Chris Zelnak describe the benefits of using EJBs ...

The bean implementation class is a regular Java class, also sometimes called a POJO, or a plain-old Java object. It does not implement an EnterpriseBean type.